Multilayer gratings are increasingly popular optical elements at X-ray beamlines, as they can provide much higher photon flux in the tender X-ray range compared with traditional single-layer coated gratings. While there are several proprietary software tools that provide the functionality to simulate the efficiencies of such gratings, until now the X-ray community has lacked an open-source alternative. Here MLgrating is presented, a program for simulating the efficiencies of both multilayer gratings and single-layer coated gratings for X-ray applications. MLgrating is benchmarked by comparing its output with that of other software tools and plans are discussed for how the program could be extended in the future.
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http://dx.doi.org/10.1107/S1600577524006271 | DOI Listing |
In this work, a specially designed multilayer indium tin oxide (ITO) mesh structure metasurface was proposed as a microwave absorber, achieving both excellent angle-insensitive broadband absorption and high shielding effectiveness (SE). It features gradually changing surface resistance ( ), to expand the absorption bandwidth while maintaining high SE. Also, a folded square ring metasurface was designed to effectively suppress surface wave grating lobes, as well as to reduce the unit size of the metasurface and thus the absorber.
View Article and Find Full Text PDFFluorescence emission regulation is of great interest for its promising applications in various fields such as microscopy, chemical analysis, encryption, and sensing. Most studies focus on the regulation of the fluorescence emission process. However, the spectral separation of excitation and emission of fluorophores requires careful design of resonances to cover both emission and excitation wavelengths, which is a better choice to enhance fluorescence intensity.
View Article and Find Full Text PDFNanoscale
December 2024
Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Manipulating circular dichroism in chiral metasurfaces has been increasingly important for a wide range of polarization-sensitive photonic applications. However, simple methods for presenting chiral nanostructures with tunable and considerable chiroptical responses in the near-infrared-I regime remains underexplored. Herein, two sheets of suspended symmetric bilayer metagratings fabricated single-step electron beam lithography are stacked into a moiré metasurface with its circular dichroism value reaching up to 20.
View Article and Find Full Text PDFThis paper addresses the burning issue of both low transmission and limited extinction ratio in polarizers based on a single layer subwavelength grating in short infrared wavelengths. In this work, an alternative polarizer with four layers of subwavelength gratings in gold, encapsulated in silica, was developed. Systematic simulations using the finite-difference time-domain (FDTD) method were carried out in designing the polarizer for the structural dimensions to ensure the highest transmission and the highest extinction ratio.
View Article and Find Full Text PDFMicromachines (Basel)
October 2024
Key Laboratory of Luminescence Science and Technology, Chinese Academy of Sciences, Changchun 130033, China.
Since surface relief transmission gratings have very strict requirements on operators and use environment, according to the semiconductor laser external cavity spectral beam combining system, this paper proposes a design scheme for a semiconductor laser array spectral beam combining system based on the grating-external cavity. The finite element approach was used to create a wideband, high-efficiency fill-in multilayer dielectric transmission grating structure for a high-power spectrum beam combining system. The incidence angle, ridge height, duty cycle, and sidewall inclination angle of the transmission grating were tuned and evaluated, and a link between the transmission grating's diffraction efficiency and grating characteristics was discovered.
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